Enantioselective C(sp 3 )‒H bond activation by chiral transition metal catalysts

Left- or right-handed C–H bond activation Although organic compounds consist mostly of carbon and hydrogen atoms, strategies for chemical synthesis have traditionally targeted the handful of more reactive interspersed oxygens, nitrogens, and halogens. Modifying C–H bonds directly is a more appealing approach, but selectivity remains a challenge. Saint-Denis et al. review recent progress in using transition metal catalysis to break just one of two mirror-image C–H bonds and then append a more complex substituent in its place. Ligand design has proven crucial to differentiate these otherwise similar bonds in a variety of molecular settings. Science , this issue p. eaao4798